In recent, various portable terminals such as smartphones, smart pads, etc. are widely used, and as an electrical source for such portable terminals, a chargeable secondary cell (hereinafter, briefly referred to as “battery”) is generally used. A lithium-ion battery is a most widely-used battery in the portable terminal, but easily generates heat in a state of overcharge or overcurrent. Further, if heat generation is continued in the lithium-ion battery and a temperature thereof rises, a performance of the battery is deteriorated and also a risk of explosion is shown.
Therefore, a portable terminal battery pack of the conventional lithium-ion battery etc. contains a protection circuit module (hereinafter, briefly referred to as “PCM”) which detects and interrupts the overcharge, overdischarge and overcurrent.
FIGS. 1a and 1b show circuit diagrams of conventional battery protection device, respectively. As illustrated in FIGS. 1a and 1b, the circuit of the conventional battery protection device mainly includes a protective IC (U0) containing two FETs (not illustrated) functioning as a switching element, a plurality of resistors (R1˜R3), and a plurality of capacitors (C1˜C2), etc. Meanwhile, the circuit in FIG. 1b further has a function of NFC (Near Field Communication) when compared to the circuit in FIG. 1a. 
In FIG. 1, a “B+” terminal and a “B−” terminal are terminals connected to a battery cell and correspond to an input side of the PCM. A “P+” terminal and a “P−” terminal correspond to an output side of the PCM. Through these terminals, charging and discharging are performed across the PCM. Finally, a “CF” terminal is an ID terminal indicating the type of battery and is connected to the “P−” terminal via the resistor (R3), wherein a resistance value of the connected resistor determines a charge current. A “DUMMY” terminal is a terminal to which a metallic spacer described later is welded, and is electrically insulated from other components. That is, the “DUMMY” terminal does not have any electrical characteristics and is necessary only for mechanical fixation, and thus may be omitted according to circumstances.
FIGS. 2a to 2c show a top view, front view and bottom view of a conventional battery protection device, respectively. As illustrated in FIGS. 2a to 2c, the conventional battery protection device has longitudinal and transverse lengths approximately equal to those of a battery cell (40) so that the device can be mounted on an upper surface of the battery cell (40). Further, the conventional battery protection device includes a double-sided PCB (10) having patterns formed on its upper and lower surfaces, respectively.
In the configuration described above, mounted on the lower surface of the PCB are the protective IC, a circuit element (30) such as the plurality of resistors and capacitors, and a thermistor (32) as described above, while a plurality of pads, e.g. “P+” terminal, “CF” terminal and “P−” terminal are exposed on the upper surface. Reference numeral “12” in the figures designates an exposure hole which is formed through the PCB (10) to expose the thermistor (32) so that the thermistor (32) can be spot-welded to the battery cell (40).
Reference numeral “50” designates a structure made of insulating material, e.g. synthetic resin, which is interposed between the battery cell (40) and the PCB (10) of the PCM in order to electrically insulate the PCM circuit elements (30, 32) from the battery cell (40) and stably fix the PCM. Reference numeral “20” designates approximately “”-shaped metallic spacers which are attached to both end portions of the lower surface of the PCB (10), respectively to join the PCB (10) to the upper surface of the battery cell (40) by means of spot-welding for example.
By the construction described above, each metallic spacer (20) has a horizontal extension part (22) spot-welded to the PCB (10), a vertical wall part (24) vertically extending from an end of the horizontal extension part (22) with a height at least equal to thickness of the structure (50) made of synthetic resin, and a horizontal extension part (26) horizontally extending from other end of the vertical wall part (24) and spot-welded to the battery cell (40).
However, according to the conventional battery protection device as described above, the metallic spacers (20) separate from the PCB (10) have to be prepared and such metallic spacers (20) have to be soldered to the PCB (10) by means of SMT (Surface Mounting Technology), and thus there is a problem that much work time is required and the number of processes is increased, that is, a productivity is lowered. Also, there is further problem that a defect rate increase since alignment in a soldering process by means of the SMT process is difficult.